1. Field of the Invention
The present invention relates to a vehicle, in particular a rail vehicle, with a wagon body and a running gear, on which the wagon body is supported, wherein the wagon body and the running gear define a vehicle longitudinal direction, a vehicle transverse direction and a vehicle height direction. A tilting mechanism is arranged between the wagon body and the running gear, which is designed to impose upon the wagon body, during a transverse displacement in the vehicle transverse direction, a rolling motion about a rolling axis parallel to the vehicle longitudinal direction.
2. Description of Related Art
In rail vehicles—but also in other vehicles—, as a rule, the wagon body is spring mounted with respect to the wheel units (for example individual wheels, pairs of wheels or sets of wheels) via one or a plurality of spring stages. Many problems of a travel dynamics nature arise, not least due to the increasingly stringent requirements regarding the safety of the vehicles, passenger comfort, as well as the transport capacity and the service life of the vehicles.
The centrifugal acceleration occurring when negotiating a curve and acting transverse to the travel movement and, therefore, transverse to the vehicle longitudinal axis, due to the comparatively elevatedly located center of gravity of the wagon body, leads to a tendency of the wagon body to incline curve-outwardly relative to the wheel units, and thus to execute a rolling motion about a rolling axis parallel to the vehicle longitudinal axis.
Above specific threshold values, such rolling motions are, on the one hand, detrimental to travelling comfort. On the other hand, they are associated with the danger of failing to comply with the permissible load gauge profile, and also, as regards the tilting stability and thus also the derailment safety, the danger of unallowable unilateral wheel unloadings. In order to prevent this, roll stabilisers as well as active or passive tilting systems are commonly used in modern rail vehicles, which counteract excessive rolling and tilting motions and also adjust the rolling and tilting angles, respectively, and the rolling axis of the vehicle to a value that is adapted to the respective travel state and optimized as far as possible. Such an approach is known for example from EP 1 190 925 A1 (the entire disclosure of which is incorporated herein by reference).
The aforementioned roll stabilisers are known in various hydraulically or purely mechanically acting embodiments. Often, a torsion shaft running transverse to the vehicle longitudinal direction is used. Levers, which are installed in a rotationally rigid manner and extend in the vehicle longitudinal direction, are mounted on this torsion shaft on both sides of the vehicle longitudinal axis. These levers are in turn connected to connecting rods, which are arranged kinematically parallel to the spring devices of the vehicle. When the spring devices of the vehicle are compressed the levers mounted on the torsion shaft are displaced in a rotational movement via the connecting rods that are joined to them.
In the rail vehicle known from EP 1 190 925 A1, the upper ends of the two connecting rods of the roll stabiliser are displaced (in a plane running perpendicular to the vehicle longitudinal axis) towards the center of the vehicle. In this way, the wagon body during a deflection in the vehicle transverse direction (caused for example by the centrifugal acceleration when negotiating a curve) is guided in such a way that a curve-outward rolling motion of the wagon body is counteracted and an curve-inwardly directed rolling motion is imposed upon the wagon body.
This oppositely directed curve-inward rolling motion serves inter alia to increase the so-called tilting comfort for the passengers of the vehicle. A high tilting comfort is normally understood in this connection to mean that the passengers, when negotiating a curve, experience as small a transverse acceleration as possible in the transverse direction of their reference system, which, as a rule, is defined by the fixtures of the wagon body (floor, walls, seats, etc.). Due to the curve-inward tilting of the wagon body resulting from the rolling motion the passengers experience (depending on the degree of tilting) at least a part of the transverse acceleration actually acting in the fixed terrestrial reference system, simply as an increased acceleration in the direction of the vehicle floor, which, as a rule, is felt to be less annoying and unpleasant, respectively.
The maximum permissible values for the transverse acceleration acting in the reference system of the passengers (and the setpoint values for the tilting angle of the wagon body ultimately resulting therefrom) are, as a rule, predetermined by the operators of a rail vehicle. National as well as international standards (such as for example EN 12299) also provide reference points for this purpose.
In this connection, in the vehicle known from EP 1 190 925 A1 it is possible to implement a purely passive system, in which the components of the spring arrangement and of the roll stabilisers are matched to one another so that the desired tilting of the wagon body is achieved solely by the transverse acceleration acting when negotiating a curve.
For such a passive solution, on the one hand, the rolling axis and the instantaneous center of rotation of the rolling motion must lie comparatively high above the center of gravity of the wagon body. On the other hand, the spring arrangement must be designed to be comparatively soft in the transverse direction, in order to achieve the desired deflections with the acting centrifugal force alone. Such a laterally soft spring arrangement also has a positive effect on the so-called vibration comfort in the transverse direction, since impacts in the transverse direction can be absorbed and damped by the soft spring arrangement.
These passive solutions, however, have the disadvantage that, due to the laterally soft spring arrangement and the elevatedly located instantaneous center of rotation, comparatively large transverse deflections in the transverse direction occur not just in normal operation but also in unplanned situations (for example an unforeseen stop of the vehicle in a track curve with a large track superelevation), as a result of which either the typically pre-set load gauge profile is infringed or (in order to prevent this) only comparatively narrow wagon bodies with a reduced transport capacity can be implemented.
The problem of the large deflections in order to achieve a specific rolling angle can of course be reduced by displacing the position of the rolling axis and the instantaneous center of rotation in the direction of the wheel support plane, so that the instantaneous center of rotation is displaced to be relatively close to the center of gravity (to a distance of about 0.3 to 1 m). However, herewith, only significantly smaller rolling angles can be achieved passively. Accordingly, the system therefore additionally stiffens in the transverse direction (since, in the roll stabiliser system, as a rule, all bearings are designed to be very stiff anyway), so that compromises have to be made not only in terms of tilting comfort but also in vibration comfort.
In addition, the kinematics produce a coupling of the two running gears of a wagon body in such a way that, in rotation movements of the wagon body with respect to the running gear (i.e. a yaw motion about a yaw axis parallel to the vehicle height direction), the vehicle is subjected to vehicle twisting possibly leading to wheel unloadings and adversely affecting derailment safety. With double-deck vehicles the instantaneous center of rotation can in addition lie very close to the upper deck of the railcar, which has a significant deleterious effect on comfort in the upper deck.
The rolling motion adapted to the curvature of the track curve actually negotiated and the actual travel speed (and therefore also the actual resultant transverse acceleration) can in the case of the vehicle known from EP 1 190 925 A1 also be actively influenced and adjusted, respectively, by an actuator provided between the wagon body and the running gear frame. In this case, a setpoint value for the rolling angle of the wagon body is determined from the actual track curvature and the actual travel speed, which is then used to adjust the rolling angle via the actuator.
This variant, of course, opens up the possibility of implementing laterally stiffer systems with smaller transverse deflections. It has the disadvantage, however, that the vibration comfort suffers owing to the transverse stiffness introduced by the actuator, so that, for example, transverse impacts on the running gear (for example when travelling over switches or defective parts in the rail) are transmitted in a less damped manner to the wagon body.
In order to compensate at least the disadvantages as regards the vibration comfort by a laterally stiff spring arrangement, it is proposed in WO 90/03906 A1 for a passive system, to incorporate a laterally soft additional spring stage kinematically in series with the tilting and rolling compensation device. This solution has the disadvantage, however, that it increases the necessary installation space due to the additional components. In addition, in this case too, there are again the problems mentioned above as regards the large transverse deflections and the reduced transport capacity.
Accordingly, it is the object of the present invention to provide an actuator and a vehicle, respectively, of the type mentioned initially, which does not have the aforementioned disadvantages, or at least on a reduced extent, and, in particular, provides a high degree of comfort for passengers in a simple and reliable manner with a compact, space-saving design.